If $OP = 1\,\,cm$ and $OS = 2\,\, cm$, work done by electric field in shifting a point charge $\frac {4\sqrt 2}{27}\,\, μC$ from point $P$ to $S$ in given figure is

If $3$ charges are placed at the vertices of equilateral triangle of charge ‘$q$’ each. What is the net potential energy, if the side of equilateral triangle is $l\, cm$

${\rm{ }}1\,ne\,V{\rm{ }} = {\rm{ }}......\,J.$ (Fill in the gap)

An electron (charge = $1.6 \times {10^{ - 19}}$ $coulomb$) is accelerated through a potential of $1,00,000$ $volts$. The energy required by the electron is

The mean free path of electrons in a metal is $4 \times 10^{-8} \;m$. The electric field which can give on an average $2 \;eV$ energy to an electron in the metal will be in units of $V / m$

In the figure the charge $Q$ is at the centre of the circle. Work done is maximum when another charge is taken from point $P$ to